Operation method for a gas-liquid ejector

ABSTRACT

The invention pertains to the field of jet technology and essentially relates to a method of operation including discharge of a motive liquid from a nozzle of a liquid-gas ejector, mixing of the motive liquid with an evacuated gaseous medium and simultaneous compression of the gaseous medium, collecting of the sprayed part of the motive liquid flow with further discharge of this collected liquid from the ejector by gravity or using a pumping action. This operational method for a liquid-gas ejector provides an increased efficiency factor for the ejector.

TECHNICAL FIELD

This invention pertains to the field of jet technology, primarily todevices for evacuation or compression of gaseous mediums.

BACKGROUND

An operational method of a liquid-gas ejector is known, which includesfeeding of a motive liquid under pressure into the ejector's nozzle,discharge of the motive liquid from the nozzle and evacuation of agaseous medium by the motive liquid (see SU, certificate of authorship,1195074, cl. F 04 F/54,1985).

This method allows evacuation of various gases by a motive liquidcirculating in a closed loop. But this method does not provide completeand effective utilization of the energy of the motive liquid, whichreduces effectiveness of liquid-gas ejector's operation.

The closest analogue of the method introduced in the present inventionis a method of operation of a liquid-gas ejector, which includes feedingof a motive liquid under pressure into the ejector's nozzle, dischargeof the motive liquid from the nozzle, evacuation of a gaseous medium bythe motive liquid, mixing of the two mediums with simultaneous partialtransfer of kinetic energy from the motive liquid to the evacuatedgaseous medium and consequent compression of the gaseous medium, formingof a gas-liquid mixture and its further discharge from the ejector (seeRU, patent 2016268, cl. F 04 F 5/54,1994).

The above described operational method of a liquid-gas ejector providesevacuation of various gaseous mediums, generation of a vacuum in anevacuated reservoir and compression of the evacuated gaseous medium.However, this method is characterized with rather big losses of energyof the motive liquid because of irrational energy transfer at theinitial stage of interaction between the motive liquid and evacuatedgaseous medium.

SUMMARY OF THE INVENTION

The present invention is aimed at an increase of the efficiency factorof a liquid-gas ejector by reducing losses of energy of the ejectorsmotive liquid.

The recited problem is solved as follows. An operational method for aliquid-gas ejector, which includes feeding of a motive liquid into theejector's nozzle, discharge of the motive liquid from the nozzle,evacuation of a gaseous medium by the motive liquid, mixing of the twomediums with simultaneous partial transfer of kinetic energy from themotive liquid to the evacuated gaseous medium and consequent compressionof the gaseous medium, forming of a gas-liquid mixture and its furtherdischarge from the ejector, is modified so that after discharge from thenozzle the peripheral part of the motive liquid flow is separated fromthe main flow, collected and discharged from the ejector in order toprevent penetration of the collected portion of the motive liquid into amixing chamber of the ejector.

The collected portion of the motive liquid can be discharged from theejector by gravity or using a pumping action.

Experimental research into operation of liquid-gas ejectors showed, thatduring discharge of a motive liquid from the ejector's nozzle (no matterwhether single-channel or multi-channel), the peripheral part of themotive liquid flow consisting mainly of fine drops loses kinetic energymuch faster than the remaining part of the liquid flow while coming intocontact with an evacuated gas. In fact this peripheral portion of themotive liquid becomes a medium to be evacuated. While hitting withmolecules of the evacuated gas, the peripheral part of the liquid flowis sprayed in a receiving chamber and settles on the walls of itsdownstream section. The sprayed portion of the motive liquid streamsdown under gravity and under influence of the gas flow and isaccumulated in the receiving chamber. As the sprayed portionaccumulates, it starts to flow into the mixing chamber. If the ejectoris placed horizontally the accumulated portion of the motive liquid isalso able to penetrate the pipeline, through which the evacuated gaseousmedium flows into the ejector. If the motive liquid collected in thereceiving chamber enters the mixing chamber the energy of non-sprayedpart of the motive liquid flow is consumed not only for evacuation ofthe gaseous medium, but also for pumping of this “passive” portion ofthe motive liquid through the ejector's flow-through channel. All ofthis negatively affects performance of the ejector.

Penetration of the “passive” portion of the motive liquid into the gassupply pipeline results in encountering a higher hydraulic resistance inthis pipeline, such that extra energy consumption is required toovercome this additional resistance.

Collecting of the sprayed peripheral part of the motive liquid flow in aspecial cavity arranged in the ejector's receiving chamber and followingdischarge of the collected liquid from the receiving chamber preventsingress of the “passive” motive liquid into the mixing chamber or intothe gas supply pipeline and eliminates its negative influence onperformance of the liquid-gas ejector.

Depending on the mode of the ejector's operation and its position(horizontal or vertical, the ejector's height relative to the otherelements of the system), there are two variants for discharge of themotive liquid accumulated in the receiving chamber—by gravity or using apumping action. The discharge by gravity is possible for the most partwhen the liquid-gas ejector is used for producing a vacuum, because inthis case a barometric pipe can be used as the drain pipe for dischargeof the accumulated liquid. If the liquid-gas ejector is used for otherpurposes (for example for gas compression), it is preferable to pump outthe motive liquid collected in the receiving chamber.

BRIEF DESCRIPTION OF DRAWINGS

The drawing in FIG. 1 represents a schematic diagram of a liquid-gasejector implementing the described operational method.

DETAILED DESCRIPTION

The liquid-gas ejector comprises a receiving chamber 1, a nozzle 2, amixing chamber 3, a drain line 4, a cavity 5, where the sprayedperipheral part of the motive liquid flow is collected before discharge.The cavity 5 can be formed by the wall of the inlet section of themixing chamber 3 and walls of the downstream section of the receivingchamber 1. The motive liquid collected in the cavity 5 can be dischargedfrom the receiving chamber 1 into a separator 6, receiving a gas-liquidflow from the ejector. Forced evacuation of the motive liquid from thecavity 5 of the receiving chamber 1 can be effected by a pump 7, whichfeeds the motive liquid under pressure into the ejector's nozzle 2.

The liquid-gas ejector implements the operational method as follows.

A motive liquid is fed under pressure from the separator 6 into thenozzle 2 of the liquid-gas ejector by the pump 7. The motive liquidflowing from the nozzle 2 entrains an evacuated gaseous medium from thereceiving chamber 1 to the mixing chamber 3. In the mixing chamber 3 amixture of the motive liquid and evacuated gaseous medium is transformedinto a gas-liquid flow, at the same time compression of the gaseousmedium takes place. Then the gas-liquid mixture is discharged from theejector and flows to its destination, for example to the separator 6where the motive liquid is separated from the compressed evacuated gas.Simultaneously, during discharge from the nozzle 2 the peripheral partof the motive liquid flow is partially sprayed in the receiving chamber1 because of its interaction with the evacuated gaseous medium. Then thesprayed portion of the motive liquid is accumulated gradually in thedownstream section of the receiving chamber 1, where the collectingcavity 5 is formed. In case of a vertical or nearly vertical position ofthe ejector the sprayed portion of the motive liquid is accumulated inthe cavity 5 at the inlet section of the mixing chamber 3. The wall ofthe inlet section of the mixing chamber 3 forming the cavity 5 in thereceiving chamber 1 prevents penetration of the sprayed portion of themotive liquid into the mixing chamber 3. Finally the sprayed portion ofthe motive liquid collected in the cavity 5 flows into the drain line 4.Subject to the mode of the ejector's operation, the liquid is dischargedfrom the cavity 5 through the drain line 4 into the separator 6 bygravity or is evacuated from the cavity 5 by the pump 7.

Thus, collecting of the sprayed peripheral part of the motive liquidflow in the receiving chamber and subsequent discharge of this liquidfrom the ejector provide an increase in the efficiency of the ejectordue to a more rational utilization of energy of ejector's motive liquid.

INDUSTRIAL APPLICABILITY

The invention can be applied in chemical, petrochemical and some otherindustries.

What is claimed is:
 1. An improved operational method for a liquid-gasejector, where the operational method includes feeding a motive liquidunder pressure into a nozzle, discharging the motive liquid from thenozzle, evacuating a gaseous medium by the motive liquid, mixing themotive liquid and the evacuated gaseous medium in a mixing chamber,partially transferring kinetic energy from the motive liquid to theevacuated gaseous medium, compressing the gaseous medium, forming agas-liquid mixture in the liquid-gas ejector and discharging thegas-liquid mixture from the liquid-gas ejector, comprising: collecting aperipheral part of the motive liquid flow after discharge of the motiveliquid from the nozzle; and discharging the collected peripheral part ofthe motive liquid from the liquid-gas ejector prior to penetration ofthe collected peripheral part of the motive liquid into the mixingchamber.
 2. The method according to claim 1, wherein said step ofdischarging the collected peripheral part of the motive liquid isperformed by gravitationally forcing the collected peripheral art of themotive liquid from the liquid-gas ejector.
 3. The method according toclaim 1, wherein said step of discharging the collected peripheral partof the motive liquid is performed by evacuating by pumping the collectedperipheral part of the motive liquid from the liquid-gas ejector.